Compressed .ISO disk image file used for archiving PlayStation Portable (PSP) games; can incorporate up to nine layers of compression; created by program such as Prometeus and YACC (Yet Another CSO Compressor).

File created by compiled .HLSL files written in High Level Shader Language (HLSL), which is shading language developed by Microsoft; contains a compiled shader object, which derives from a HLSL file; retains the same name as the HLSL file but appears as a CSO file after the compile in Microsoft Visual Studio.

In the OpenGL SDK, CSO files can be compiled using the glCompileShader method. glCompileShader compiles HLSL strings into the shader object. Information about whether or not a compilation was successful can be obtained through the shader object's information log by calling glGetShaderInfoLog.